1. Field of the Invention
The present invention relates to a method for substrate cleaning of liquid crystal display and, more particularly, to an apparatus for substrate cleaning of liquid crystal display capable of controlling exhaust during substrate cleaning and a method of substrate cleaning using it.
2. Description of the Related Art
As is generally known, liquid crystal display manufacturing methods comprise an array process and a cell process. The array process includes the steps of making film and forming fine patterns on a lower glass substrate by photolithography and the cell process includes the steps of implanting liquid crystals by adhering the lower glass substrate and an upper glass substrate as a color filter substrate, wherein cleaning processes are performed to remove injurious impurities on the substrates during the processes. The cleaning process makes up 20xcx9c30% of whole process, removing different impurities in each process, thereby it is required to provide different cleaning apparatus by the process.
The cleaning apparatus is divided into a batch type and sheet fed type. In the batch type, substrates are cleaned by a cassette unit. On the other hand, the sheet fed type comprises the steps of carrying a plurality of substrates, cleaning the substrates with brush or ultrasonic waves and drying them with air knife or spin dry. The sheet fed type can be advantageously applied to large scale substrates.
FIG. 1 is a drawing showing an apparatus for substrate cleaning and a method for substrate cleaning using it according to a conventional art, wherein a substrate cleaning apparatus is provided with spin dry unit.
As shown in FIG. 1, the spin dry unit 10 comprises a spin dry cup 15 having a rotation device 12 for rotating a substrate 14, an exhaust duct 18 arranged on the lower part of spin dry cup 15 to exhaust impurities, chemicals and water from the rotating substrate 14 to external and an exhaust damper arranged on the exhaust duct 18 to control exhaust volume.
The substrate cleaning method using the above-mentioned apparatus will be described in the following.
First, a substrate 14 is rotated on a predetermined rotation device 12, thereby exhausting impurities of the substrates 14 to an exhaust duct 18 through a normally open exhaust damper 16 by centrifugal force and airflow.
FIG. 2 shows an example of substrate cleaning apparatus of liquid crystal display device according to a conventional art.
As shown in FIG. 2, the substrate cleaning apparatus comprises 9 devices and 3 spin dry units are connected to each device, thereby amounting to 27 spin dry units. All of the 27 spin dry units are connected to a main duct 20 to exhaust waste gas from each spin dry unit to external through the main duct 20.
However, the conventional substrate cleaning apparatus having a spin dry unit and the substrate cleaning method using it have several problems as follows.
As the size of liquid crystal panel is increased, the rotation speed is also increased, thereby providing great centrifugal force to impurities on the substrate. Therefore, impurities are frequently bumped against the wall of spin dry unit by rising currents and returned to the substrate. In order to solve the problem, large amount of air is absorbed from the external and much exhaust is required during substrate cleaning. When exhaust is insufficient, that is, exhaust pressure is not sufficiently provided in each unit, defective rates are increased by rising currents due to centrifugal force during spin dry process.
Therefore, the present invention has been proposed to solve the problems of conventional arts and an object of the present invention is to provide a substrate cleaning apparatus of liquid crystal display capable of reducing the manufacturing cost and improving process margin by reinforcing down flow in the device with small amount of exhaust, wherein a normally open mode of spin dry unit is changed into a normally close mode by signal modification and recipe modification.
Another object of the present invention is to provide a substrate cleaning method of liquid crystal display capable of reducing the manufacturing cost and improving process margin by reinforcing down flow in the device with small amount of exhaust, wherein a normally open mode of spin dry unit is changed into a normally close mode by signal modification and recipe modification.
In order to accomplish the above objects, the substrate cleaning apparatus of the present invention comprises: a spin dry cup having a rotation device for rotating a substrate; an air absorber arranged on the external of the spin dry cup to absorb air and impurities exhausted from the rotating substrate; a trap for exhausting air and impurities absorbed from the air absorber to the external; an exhaust pressure control unit arranged on the trap to control exhaust pressure therein; and a drain arranged on the trap to exhaust chemicals and water from the rotating substrate to the external.
The substrate cleaning method using the present substrate cleaning apparatus comprises the steps of: providing a substrate cleaning apparatus according to claim 3; loading the substrate on a rotation device; and closing a manual damper by hand operation and then automatically operating an auto damper when the substrate is loaded on the rotation device and cleaning process is performed.